This invention relates to communication switching systems for selectively establishing two-way communication paths between desired ones of a set of telephone instruments or other two-way communication peripheral devices, and deals more particularly with such a switching system of the type commonly referred to as a private automatic branch exchange (PABX) for servicing a relatively small number of telephone instruments or the like such as, for example, those used in a given office, factory, government agency or similar business establishment.
The communication system of this invention may be an isolated one used only to interconnect a fixed group of telephones or similar peripheral devices to one another. Or, it may be connected to other outside telephones or devices through one or more trunk lines, or other connecting lines, as in the embodiment hereinafter illustrated and described in detail.
In either event, the general object of this invention is to provide a communication switching system or PABX which is an improvement in various different ways over similar systems currently available. Among these improvements are, a low per station cost for the system, ease in installing and maintaining the system, speedy operation in setting up and disconnecting communication paths and handling other service requests, and the ability to provide various different system features, such as camp-on, call forwarding, call conferencing, call hold, etc. largely through programming of the processor memory and without the need for keys on the telephone instruments.
Other objects and advantages of the invention will be apparent from the drawings and from the following detailed discussion and claims.